The phrase "affect an attitude" is correct and usable in written English.
You can use it in a sentence to describe how something has an influence on or changes a person's outlook or opinion. For example, "The constant criticism of his parents affected his attitude toward schoolwork."
Shoulders hunched, chin thrust forward, gaunt frame poured into jet-colored jeans, he affected an attitude straight out of Poe.
Crystal masks her frustration and anger by affecting an attitude of tolerant superiority toward Jamie's impatience and air of entitlement.
The only defense was to become equally crass while affecting an attitude of indifference, and I did this so well that it is still difficult for me to have a conversation with a high school friend with my children in the room.
Although it affects an attitude of being fair and balanced as its poses Big Questions about faith and the existence of God, it barely camouflages its contempt for the free-spirited Gavin's righteously born-again Christian adversary, Joe Patrick Wilsonn), a pathetic, bigoted, sociopathic paper tiger of a foe.
Below are a few examples of the word "affect" being used in this way: Richard affected an attitude of indifference, though he was deeply hurt by the comments.
I used to affect a cavalier attitude to death; now I see it from my son's perspective".
Understandably, given that it has rained at 24 out of 32 Glastonburys, hardened festivalgoers tend to affect a blase attitude to inclement conditions, arriving prepared for the worst.
Try to affect a swashbucklin' attitude with your delivery.
In the Theory of Planned Behavior (TPB), an individual's behavioural beliefs and evaluations of behavioural outcomes are contributing factors that affect an individual's attitude toward the behaviours.
Various childhood factors could affect a person's attitude formation.
